U.S. patent application number 13/428041 was filed with the patent office on 2013-09-26 for composite structure forming on coefficient of thermal expansion mismatched tooling.
This patent application is currently assigned to SPIRIT AEROSYSTEMS, INC.. The applicant listed for this patent is Steven Fillmore Hanson, Randy R. Kysar. Invention is credited to Steven Fillmore Hanson, Randy R. Kysar.
Application Number | 20130248093 13/428041 |
Document ID | / |
Family ID | 49210662 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130248093 |
Kind Code |
A1 |
Hanson; Steven Fillmore ; et
al. |
September 26, 2013 |
COMPOSITE STRUCTURE FORMING ON COEFFICIENT OF THERMAL EXPANSION
MISMATCHED TOOLING
Abstract
A mandrel used with forming composite parts includes an outer
surface on which composite material is placed, and a groove in
which splice material is filled. The groove may be positioned on
the outer surface along the length of the mandrel. A method for
forming composite parts includes the steps of providing a mandrel
that includes a groove aligned with its longitudinal axis, filling
the groove with splice material, cutting the composite material to
match the shape and the size of the mandrel, placing the composite
material around the outer surface of the mandrel, and curing the
composite material and the mandrel.
Inventors: |
Hanson; Steven Fillmore;
(Derby, KS) ; Kysar; Randy R.; (Derby,
KS) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hanson; Steven Fillmore
Kysar; Randy R. |
Derby
Derby |
KS
KS |
US
US |
|
|
Assignee: |
SPIRIT AEROSYSTEMS, INC.
Wichita
KS
|
Family ID: |
49210662 |
Appl. No.: |
13/428041 |
Filed: |
March 23, 2012 |
Current U.S.
Class: |
156/218 ;
156/475 |
Current CPC
Class: |
B29K 2105/08 20130101;
Y10T 156/1038 20150115; B29C 53/42 20130101 |
Class at
Publication: |
156/218 ;
156/475 |
International
Class: |
B29C 53/36 20060101
B29C053/36; B29C 63/06 20060101 B29C063/06 |
Claims
1. A mandrel for use with forming composite parts, the mandrel
comprising: an outer surface on which composite material is placed;
and a groove in which splice material is filled, the groove
positioned on the outer surface of the mandrel, the groove
providing a path along which first and second ends of the composite
material are aligned such that the composite material contacts the
splice material.
2. The mandrel of claim 1, further including a cylindrical body
with a first end and an opposing second end, wherein the groove is
aligned with the longitudinal axis of the cylindrical body and
extends from the first end to the second end.
3. The mandrel of claim 1, wherein the mandrel has a higher
coefficient of thermal expansion than does the composite
material.
4. The mandrel of claim 1, wherein the groove includes first and
second sidewalls and a bottom wall to retain the splice
material.
5. A method of forming composite material parts, the method
comprising the steps of: a) providing a mandrel that includes a
splice groove aligned with its longitudinal axis; b) filling the
splice groove with splice material; c) preparing a composite
material to form a sheet with at least one dimension that matches a
dimension of an outer surface of the mandrel, the sheet including a
first edge and an opposing second edge; d) placing the composite
material on the outer surface of the mandrel such that the first
edge is aligned with the second edge over the splice material in
the splice groove; e) curing the composite material and the mandrel
such that the composite material and the splice material foam a
monolithic part; and f) removing the part from the mandrel.
6. The method of claim 5, wherein the splice material is uncured
composite material.
7. The method of claim 5, wherein the splice material is cured
composite material.
8. The method of claim 5, wherein the splice material is a
metal.
9. The method of claim 5, wherein the mandrel has the shape of the
final composite part.
10. The method of claim 5, wherein the mandrel is roughly
cylindrical in shape.
11. The method of claim 5, wherein the splice groove includes a
bottom surface with the same cross-sectional shape as the
cross-sectional shape as an outer surface of the mandrel.
12. The method of claim 5, wherein the mandrel has a coefficient of
thermal expansion that is greater than the coefficient of thermal
expansion of the composite material.
13. A method of forming composite material parts, the method
comprising the steps of: a) providing a mandrel that includes a
splice groove aligned with its longitudinal axis; b) filling the
splice groove with splice material; c) placing a composite material
including a plurality of fibers on an outer surface of the mandrel
such that at least a portion of the fibers contact an outer layer
of the splice material; d) cutting the composite material to form a
split in the composite material above the outer layer of the splice
material in the splice groove along the entire length thereof; e)
curing the composite material and the mandrel such that the
composite material and the splice material form a monolithic part;
and f) removing the part from the mandrel.
14. The method of claim 13, wherein at least a portion of the
fibers of the composite material are placed on the mandrel at an
angle transverse to the length of the splice groove.
15. A method of forming composite material parts, the method
comprising the steps of: a) providing a mandrel that includes a
splice groove aligned with its longitudinal axis, the splice groove
including a longitudinal first edge and an opposing longitudinal
second edge; b) filling the splice groove with splice material; c)
placing a first edge of a composite material in contact with the
splice material such that a portion of the composite material
overlays the first edge of the splice groove; d) applying the
composite material to an outer surface of the mandrel; e) cutting
the composite material to form a second edge of the composite
material that opposes the first edge of the composite material; f)
aligning the second edge of the composite material with the first
edge of the composite material over the splice material in the
splice groove; g) curing the composite material and the mandrel
such that the composite material and the splice material form a
monolithic part; and h) removing the part from the mandrel.
16. The method of claim 15, wherein applying the composite material
to the outer surface of the mandrel includes applying the composite
material in a direction from the first edge of the splice groove
across the outer surface of the mandrel to the second edge of the
splice groove.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Embodiments of the present invention relate to systems and
methods for forming composite structures. More particularly,
embodiments of the present invention relate to systems and methods
for forming composite structures with a forming tool that has a
large coefficient of thermal expansion.
[0003] 2. Description of the Related Art
[0004] Composite structures may be formed by winding composite
material, such as carbon fiber, around a mold, or mandrel, in the
shape of the final structure. The combination of the mandrel and
the composite material is often subjected to high temperature in
order to cure the composite material. Wrapping the material around
the mandrel may form a closed loop. During heating, both the
mandrel and the material will expand. If the coefficient of thermal
expansion (CTE) of the mandrel is greater than the CTE of the
material, then the mandrel will experience greater expansion than
the material. If the material is wound tightly against the mandrel,
then the expansion of the mandrel will exert a force on the
material that creates tension in the fibers. A large enough tension
may break a sufficient number of fibers to weaken the final
structure and render it unusable.
SUMMARY OF THE INVENTION
[0005] Embodiments of the present invention solve the
above-mentioned problems and provide a distinct advance in the art
of forming composite structures. More particularly, embodiments of
the invention provide a method for forming composite structures
with a mandrel that has a greater coefficient of thermal expansion
than that of the composite structure material.
[0006] A mandrel is provided in the shape of a composite part in
its final form. The mandrel may include an outer surface on which
composite material is placed, and a groove in which splice material
is filled. The groove may be positioned on the outer surface along
the length of the mandrel. The groove may also provide a path along
which first and second ends of the composite material are aligned
such that the composite material contacts the splice material and
bonds to the splice material when the composite material and the
mandrel are cured. A method for forming the composite part includes
the steps of providing a mandrel that includes a groove aligned
with its longitudinal axis, filling the groove with splice
material, cutting the composite material to match the shape and the
size of the mandrel, placing the composite material around the
outer surface of the mandrel, and curing the composite material and
the mandrel.
[0007] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the detailed description. This summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used to limit the scope of the claimed
subject matter.
[0008] Other aspects and advantages of the present invention will
be apparent from the following detailed description of the
embodiments and the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0009] Embodiments of the present invention are described in detail
below with reference to the attached drawing figures, wherein:
[0010] FIG. 1 is a perspective view of a mandrel including a
longitudinal groove used to form a composite structure in
accordance with various embodiments of the present invention;
[0011] FIG. 2 is an enlarged front view of the groove;
[0012] FIG. 3 is a perspective view of the mandrel depicting the
groove filled with splice material;
[0013] FIG. 4 is an enlarged front view of the groove filled with
splice material;
[0014] FIG. 5 is a perspective view of the mandrel depicting a cut
in the composite material over the groove;
[0015] FIG. 6 is an enlarged front view of the groove depicting the
cut in the composite material over the groove;
[0016] FIG. 7 is a perspective view of a finished composite
structure; and
[0017] FIG. 8 is a flow diagram depicting a least a portion of the
steps of a method of forming composite parts.
[0018] The drawing figures do not limit the present invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] The following detailed description of the invention
references the accompanying drawings that illustrate specific
embodiments in which the invention can be practiced. The
embodiments are intended to describe aspects of the invention in
sufficient detail to enable those skilled in the art to practice
the invention. Other embodiments can be utilized and changes can be
made without departing from the scope of the present invention. The
following detailed description is, therefore, not to be taken in a
limiting sense. The scope of the present invention is defined only
by the appended claims, along with the full scope of equivalents to
which such claims are entitled.
[0020] In this description, references to "one embodiment", "an
embodiment", or "embodiments" mean that the feature or features
being referred to are included in at least one embodiment of the
technology. Separate references to "one embodiment", "an
embodiment", or "embodiments" in this description do not
necessarily refer to the same embodiment and are also not mutually
exclusive unless so stated and/or except as will be readily
apparent to those skilled in the art from the description. For
example, a feature, structure, act, etc. described in one
embodiment may also be included in other embodiments, but is not
necessarily included. Thus, the present technology can include a
variety of combinations and/or integrations of the embodiments
described herein.
[0021] A mandrel 10 for forming composite structures using
composite material, constructed in accordance with various
embodiments of the current invention, is shown in FIGS. 1-6. The
mandrel 10 may present the shape of the composite structure to be
formed. For example, when forming a composite structure used to
manufacture an aircraft fuselage, the mandrel 10 may present a
generally elongated cylindrical shape with dimensions that are
similar to those of the fuselage. In various embodiments, the
mandrel 10 may be solid. In other embodiments, the mandrel 10 may
be hollow or have a generally tubular shape. The mandrel 10 is
typically constructed from a metal, such as aluminum, that can
withstand compressive forces when the composite structure is being
formed. Generally, the mandrel 10 includes an outer surface 12
along its circumference, a first end 14, and an opposing second end
16. The mandrel 10 may have an exemplary diameter of approximately
6 feet to approximately 30 feet and an exemplary length of
approximately 10 feet to approximately 100 feet.
[0022] The mandrel 10 further includes a groove 18 that is
generally positioned on the mandrel 10 in the area or areas where
composite material fibers will be wound. Furthermore, the groove 18
is typically oriented such that at any point along the groove 18,
the groove 18 is positioned transverse or at an approximate right
angle to the direction of the winding of the fibers. In various
embodiments, the groove 18 may have a shape as required by the
final part. In some embodiments, the groove 18 may have a curvature
along its length. In exemplary embodiments, the groove 18 may be
positioned along the outer surface 12 and in alignment with the
longitudinal axis of the mandrel 10 such that the groove 18 extends
from the first end 14 to the second end 16. The groove 18 may
include a first sidewall 20 and an opposing second sidewall 22 that
extend inward from the outer surface 12 of the mandrel 10 at an
angle. A generally curved bottom wall 24 (that matches the
curvature of the mandrel 10) may connect from the first sidewall 20
to the second sidewall 22. In various embodiments, the first
sidewall 20, the second sidewall 22, and the bottom wall 24 may
have different shapes, dimensions, or relative angles, such that
the groove 18 may have a variety of cross-sectional profiles. An
exemplary groove 18 may have dimensions of approximately 6 inches
to approximately 24 inches in width. In general, the groove 18 is
shaped to retain material that is placed within the groove 18 to
form a co-cured splice.
[0023] The composite material 28, as shown in FIGS. 5-6, generally
includes at least two constituent components--a reinforcement
material and a matrix material. The reinforcement material
generally provides mechanical strengthening properties, such as
high tensile strength, to the composite material, while the matrix
material acts as a binder to hold the reinforcement material
together. The reinforcement material and the matrix material may
possess additional properties not discussed herein. Furthermore,
the composite material may include additional components not
discussed herein.
[0024] Examples of the reinforcement material that may be used with
the current invention include, but are not limited to, fiber
materials such as carbon fiber, boron fiber, fiberglass, aramid
fiber, ceramic fiber, and the like. In the case of fiber-based
reinforcement materials, the fiber may exist in one of at least two
forms--either preimpregnated (prepreg), in which the fiber may be
coated with a matrix material that is uncured, such as uncured
resin, or as dry fiber, with no matrix material incorporated prior
to part manufacture. The matrix material may typically be in the
form of polymer resins, such as epoxies, bismaleimides, vinyl
esters, and the like, among others.
[0025] The composite material 28 may exist in a fiber or bundle of
fibers form, or it may exist as a sheet or a weave of fibers.
[0026] At least a portion of the steps of a method 100 of forming
composite structures using the mandrel 10 in accordance with
various embodiments of the present invention is listed in FIG. 8.
The steps may be performed in the order as shown in FIG. 8, or they
may be performed in a different order. Furthermore, some steps may
be performed concurrently as opposed to sequentially. In addition,
some steps may be omitted.
[0027] Referring to step 101, a mandrel 10 is provided that
includes a groove 18 aligned with its longitudinal axis, as seen in
FIGS. 1-2. In some embodiments, more than one mandrel 10 may be
provided. The mandrel 10 may present other shapes as necessary to
match the shape of the final part to be formed. The mandrel 10 may
include an outer surface 12 in which the groove 18 is placed, such
that the groove 18 extends from a first end 14 of the mandrel 10 to
an opposing second end 16. The groove 18 may further include a
first sidewall 20, a second sidewall 22, and a bottom wall 24, and
may be formed using techniques such as machining.
[0028] Referring to step 102, the groove 18 is filled with
composite material, as seen in FIGS. 3-4, referred to as splice
material 26, which may be cured or uncured. In some embodiments,
the splice material 26 may also be a metal such as titanium.
[0029] Referring to step 103, the composite material 28 is cut to
match the size and shape of the mandrel 10. In the case of fiber or
fiber bundle composite material 28, the composite material 28 is
cut to form strands with a length that is approximately equal to
the circumference of the mandrel 10. If the composite material 28
is a sheet or a weave, then the composite material 28 is cut to
have a width approximately equal to the circumference of the
mandrel 10. Cutting the composite material 28 generally creates a
first material end 30 and a second material end 32 on opposing
sides of the composite material 28.
[0030] Referring to step 104, the composite material 28 is placed
on the mandrel 10, such that the first material end 30 and the
second material end 32 abut each other over the groove 18 and the
splice material 26. The composite material 28 may be placed using
automated techniques or manual techniques. In various embodiments,
fiber tow placement may be used to place the composite material 28
on the mandrel 10. Generally, after placement, the first material
end 30 and the second material end 32 should touch or abut one
another over the center of the groove. In addition, it is desirable
for the first material end 30 and the second material end 32 to
touch one another, although a gap therebetween of up to 0.05 inches
may be acceptable.
[0031] Referring to step 105, the mandrel 10, the composite
material 28, and the splice material 26 are cured. The curing may
be performed in an autoclave or an oven. During the curing, the
mandrel 10 may expand as a result of the high temperature. The
circumference of the mandrel 10 may increase thereby creating
tension on the composite material 28 and increasing the separation
distance between the first material end 30 and the second material
end 32. The portions of the first material end 30 and the second
material end 32 that contact the splice material 26 may bond to the
splice material 26 and cure as a unit such that the composite
material 28 (including the first material end 30 and the second
material end 32) and the splice material 26 form a single
monolithic finished composite part 34.
[0032] Referring to step 106, the part 34, shown in FIG. 7, is
removed from the mandrel 10. The part 34 is generally ready for
use.
[0033] The method of various embodiments of the current invention
allows for lighter weight, lower cost metals with a relatively
higher coefficient of thermal expansion, such as aluminum, to be
used for the mandrel 10 while still providing a monolithic finished
composite part. Furthermore, the method results in virtually no
broken fibers and a reduced number of marcelled fibers. Thus,
finished parts are of a higher quality for a lower cost.
[0034] Although the invention has been described with reference to
the embodiments illustrated in the attached drawing figures, it is
noted that equivalents may be employed and substitutions made
herein without departing from the scope of the invention as recited
in the claims.
* * * * *